All-optical nonlinearity mitigation in fiber-optic communications
Doktorsavhandling, 2018

The two main factors limiting the data throughput in modern fiber-optic communication links are the noise added by amplifiers and the nonlinear response of the optical fiber due to the Kerr effect. Today there are communication systems operating remarkably close to the limits set by these two factors. In order to increase the data throughput in a single fiber one can attempt reducing the noise added by the amplifiers or mitigate the nonlinear distortion which is dominated by deterministic effects. The work presented in this thesis is focused on reducing the negative impact of the Kerr nonlinearity through the use of all-optical signal processing by transmission of a phase-conjugated copy alongside the signal. A concept where the phase-conjugated data is repeated in time domain is investigated and it was found that it performs comparably to the conventional phase-conjugated twin waves concept. The rest of the thesis is dedicated to studying various aspects of the two-mode copier-phase-sensitive amplifier (PSA) scheme. These studies focus both on improving the understanding and on optimizing the performance of the nonlinearity mitigation in copier-PSA links. We study the optimization of the dispersion map on a single- and two-span basis and it is shown in simulations that significant improvements can be achieved by optimization over two spans. In a numerical study it was found that there is potential for improving the efficiency of the nonlinearity mitigation by addition of dsitributed Raman amplification (DRA) in a copier-PSA link. Long-haul transmission using the copier-PSA scheme is demonstrated experimentally both with and without DRA. Without DRA at 10 Gbaud, it is shown that it is possible to improve the transmission reach by up to a factor of 5.6 with the addition of PSA. With DRA at 28 Gbaud, the improvement in transmission reach is smaller but we observe an increase in the optimum launch power when enabling the PSA indicating improved nonlinearity mitigation.

fiber-optic communications

phase-sensitive amplifiers

optical phase conjugation

nonlinear optics

Kollektor (A423), Department of Microtechnology and Nanoscience (MC2), Kemivägen 9, 412 58, Göteborg
Opponent: Andrew D. Ellis, Aston University, UK


Henrik Eliasson

Chalmers, Mikroteknologi och nanovetenskap, Fotonik

Mitigation of nonlinearities using conjugate data repetition

Optics Express,; Vol. 23(2015)p. 2392-2402

Artikel i vetenskaplig tidskrift

Comparison between Coherent Superposition in DSP and PSA for Mitigation of Nonlinearities in a Single-span Link

European Conference on Optical Communication, ECOC 2014; Cannes; France; 21 September 2014 through 25 September 2014,; (2014)p. Art. no. 6964015-

Paper i proceeding

Mitigation of nonlinear distortion in hybrid Raman/phase-sensitive amplifier links

Optics Express,; Vol. 24(2016)p. 888-900

Artikel i vetenskaplig tidskrift

Dispersion management for nonlinearity mitigation in two-span 28 GBaud QPSK phase-sensitive amplifier links

Optics Express,; Vol. 25(2017)p. 13163-13173

Artikel i vetenskaplig tidskrift

S. L. I. Olsson, H. Eliasson, E. Astra, M. Karlsson, P. A. Andrekson "Long-haul optical transmission links using low-noise phase-sensitive amplifiers"

H. Eliasson, K. Vijayan, B. Foo, S. L. I. Olsson, E. Astra, M. Karlsson, P. A. Andrekson "Phase-sensitive amplifier links with distributed Raman amplification"

An enabling technology for the internet revolution has been fiber-optic communication. Since the invention of the optical fiber in the 1960s we have seen an extraordinary development in the way we communicate and the way we access information on the internet. All of this has been made possible by ever increasing data throughput in our global network of fiber-optic communication links. Today we can build links where the amount of data that is sent through a single fiber is close to what is predicted for modern coherent fiber-optic communication systems by fundamental physics. One important limiting factor is the nonlinear Kerr effect in optical fibers, named after Scottish physicist John Kerr. The Kerr effect, inherent to the optical fiber itself, will lead to distortion of the transmitted signal at high optical powers effectively setting limits on the amount of data that can be communicated. Luckily the Kerr effect is deterministic in nature and can be undone. This thesis is devoted to the study of all-optical methods for reducing the negative impact of the Kerr effect. We investigate and demonstrate the use of phase-sensitive amplifiers with the purpose of mitigating the Kerr effect. The work presented in this thesis could prove instrumental in understanding how to combat fiber nonlinearities and allow for future technologies that can increase the amount of data that can be pushed through an optical fiber.


Informations- och kommunikationsteknik




Annan elektroteknik och elektronik


C3SE (Chalmers Centre for Computational Science and Engineering)



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4409



Kollektor (A423), Department of Microtechnology and Nanoscience (MC2), Kemivägen 9, 412 58, Göteborg

Opponent: Andrew D. Ellis, Aston University, UK

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